Electric fuse



March 15 1927.

G. 3, BROWN ELECTRIC FUSE Filed July 20, 1926 Inventor: Gear eRBrown H is Attorney.

Patented Filer. id, 192?.

STATES GEORGE R. BROTJN, F BRZDGEPORT, 6""FECTIC'UT, ASSIGNOR CQMEAIIY, A C0131 T0 GENERAL ELECTRIC :v/PLTIGN OF FETEW' YORK.

ELECTRIC FUSE.

Application filed July 20, 1926.

.closed fuses. The object of the invention is to provide an improved construction of fuse which shall operate satisfactorily under severest current conditions, to interriupt the circuit protected thereby and without danger of injury to persons or things.

lVhen a fuse operates or blows under short-circuit conditions, its fusible elementis converted in an extremely limited period of time into metallic of such l i h heat that persons a d combustible matter in the vicinity would be burned or otherwise injured if provision is not made to confine such gas until its heat become dissipated to a considerable extent. Accordingly, it is customary to enclose electrical fuses in plugs or cartridges of insulating material, and, on account of the liability of the high pressure enerated, to disrupt the insulating enclosure it is customary to'provide the latter with vents whereby the gas may escape gradually.

In order that the presence of the vents may not nullify the purpose of the insulating enclosure, 1 so arrange the vents that as passes from the insulatingenclosure it impinges upon and is allowed to expand in con tact with metal surfaces which serve to deprive it of most of its heat. and it is then di rected in its final escape into the atmosphere so that particles of metallic oxide contained therein are deposited on the outer endof the encasement and serve as an indication that the fuse has blown.

One embodiment of the invention is shown in the accompanying drawing, in which Fig. 1 is a vertical section of a fuse plug shown about double usual size, and Fig. 2 is a top plan thereof with parts broken away.

As shown in the drawing, the plug com prises a cup-shaped base 1 of porcelain or other insulating material with a screw shell contact 2 and a center contact 3 mounted thereon in well-known manner and connected by a fuse link 4t of soft metal. The cupshaped base has at its upper end an integral external flange dwith its top corner 6 chamfered, and one r more narrow vent slots or passageways 7 are cut radially across the upper end wall of the base.

An imperforate disk 8 of transparent 1n sulating material, such mica, and of a size somewhat less than that of the base fierial No. 123,752.

flange 5, is securely bound against the upper end of the base by a metal closure shell 9.

The metal closure shell 9 has a peripheral down-turned flange 10 of a size to closely surround the base flange 5, and is secured in place by spinning its lower edge 11 beneath the base flange 5. The center of the shell 9 is apertured at 12 to permit inspection of the condition of the fuse link 4 through the transparent disk 8. The aperture 12 is made relatively small in order that the greater part of the transparent disk may be sustained against the gas pressure within the plug by the metal shell 9.

The radial portion of the metal shell 9 is provided with two spaced annular beads 13 and 14: adjacentits periphery and about the centra aperture 12, respectively, and the plane portion 15 between the beads has a plurality of radial embossrnents 16 struck up therein which connect with the outer head 13 and extend to slits 17 cut adjacent the inner head 14 whereby inwardly directed exits from the gas expansion space 18 formed between the base chamfer 6 and the inside of the outer head 13 are provided.

Upon blowing of the link 4, the gases generated thereby pass in a small. stream or streams through the narrow vent slot or slots 7 at the upper end of the base, beneath the transparent disk 8, and impinge against the inner wall of the flange 10 of the metal shell 9 which acts to absorb much of the heat thereof, and after becoming expanded within the space 18 they escape through the inwardly directed exits of the radial embossments 16 and impinge upon the outer wall of the inner head 14 whereby they are deflected centrally along the axis of the plug so that they can make no objectionable deposits on the cut-out block in which the fuse is installed. On account of the gases containing particles of oxidized metal, the latter forms black deposits 19 upon the wall of the head 14, and thereby affords an indication of the fact that the fuse has blown, which may be readily observed even in dimly lighted places.

l i hile 1 have shown and described the best embodiment of the invention known to me, I do not desire to be, restricted thereto.

lVhat I claim as new, and desire to secure by Letters Patent of the United States, is:

1. An electric fuse comprising an insulating base provided with a gas passageway,

and a metal shell enclosing an end of said base and the passageway therein, said shell forming with said base an expansion chamber for the gases and having in the wall thereof inwardly opening exit passages from said chamber.

2. An electric fuse comprising an insulating base provided with a vent passageway and an end flange, and a sheet metal shell enclosing an end of said base and the passageway therein and secured to said end flange, said" shell being beaded adjacent its periphery'to form with the base a gas expansion chamberand having in the end wall thereof inwardly directed exit passages from said chamber.

3. An electric fuse comprising an insulating base provided with a gas passageway, and a metal shell enclosing an end of said base and the passageway therein, said shell forming with said base end a gas expansion chamber and having formed in the end wall thereof inwardly directed exit passages from said chamber and an outwardly inclined surface against which the exit gases impinge.

a. An electric fuse comprising an insulating base having at its end a vent passageway and a peripheral flange, a transparent disk over the end of said base, and a sheet metal shell having a central aperture secured over said base flange and holding said disk thereto, said shell having s1 aced beads struck up therein adjacent its periphery and about the aperture therein and inwardly directed exit passages extending from the interior of the peripheral bead and opening adjacent the outer wall of the bead about the central aperture thereof.

In witness whereof, I have hereunto set my hand this sixteenth day of July, 1926.

GEORGE E. BROlVN. 

